A genomic and morphometric analysis of alpine bumblebees: Ongoing reductions in tongue length but no clear genetic component.

Over the last six decades, populations of the bumblebees Bombus sylvicola and Bombus balteatus in Colorado have experienced decreases in tongue length, a trait important for plant-pollinator mutualisms. It has been hypothesized that this observation reflects selection resulting from shifts in floral composition under climate change. Here we used morphometrics and population genomics to determine whether morphological change is ongoing, investigate the genetic basis of morphological variation, and analyse population structure in these populations.

Genetic Barriers to Historical Gene Flow between Cryptic Species of Alpine Bumblebees Revealed by Comparative Population Genomics.

Evidence is accumulating that gene flow commonly occurs between recently diverged species, despite the existence of barriers to gene flow in their genomes. However, we still know little about what regions of the genome become barriers to gene flow and how such barriers form. Here, we compare genetic differentiation across the genomes of bumblebee species living in sympatry and allopatry to reveal the potential impact of gene flow during species divergence and uncover genetic barrier loci.

Flight of the bumble bee: Buzzes predict pollination services.

Multiple interacting factors drive recent declines in wild and managed bees, threatening their pollination services. Widespread and intensive monitoring could lead to more effective management of wild and managed bees. However, tracking their dynamic populations is costly.

Functional mismatch in a bumble bee pollination mutualism under climate change.

Ecological partnerships, or mutualisms, are globally widespread, sustaining agriculture and biodiversity. Mutualisms evolve through the matching of functional traits between partners, such as tongue length of pollinators and flower tube depth of plants. Long-tongued pollinators specialize on flowers with deep corolla tubes, whereas shorter-tongued pollinators generalize across tube lengths.

Bumble bee nest abundance, foraging distance, and host-plant reproduction: implications for management and conservation.

Recent reports of global declines in pollinator species imply an urgent need to assess the abundance of native pollinators and density-dependent benefits for linked plants. In this study, we investigated (1) pollinator nest distributions and estimated colony abundances, (2) the relationship between abundances of foraging workers and the number of nests they represent, (3) pollinator foraging ranges, and (4) the relationship between pollinator abundance and plant reproduction. We examined these questions in an alpine ecosystem in the Colorado Rocky Mountains, focusing on four alpine bumble bee species (Bombus balteatus, B.

Tracing impacts of partner abundance in facultative pollination mutualisms: from individuals to populations.

Partner abundance affects costs and benefits in obligate mutualisms, but its role in facultative partnerships is less clear. We address this gap in a pollination web consisting of two clovers (Trifolium) that differ in specialization on a bumble bee pollinator Bombus balteatus. We examine how pollination niche breadth affects plant responses to pollinator abundance, comparing early-flowering (specialized) and late-flowering (generalized) cohorts of T.

Density-dependent effects of ants on selection for bumble bee pollination in Polemonium viscosum.

Mutualisms are commonly exploited by cheater species that usurp rewards without providing reciprocal benefits. Yet most studies of selection between mutualist partners ignore interactions with third species and consequently overlook the impact of cheaters on evolution in the mutualism. Here, we explicitly investigate how the abundance of nectar-thieving ants (cheaters) influences selection in a pollination mutualism between bumble bees and the alpine skypilot, Polemonium viscosum.